The present invention relates to a device and to a process for the synchronization of broadcast audiovisual programs and of complementary information, as well as to corresponding applications.
In interactive television systems, a central server receives from advisory centers a program guide which contains information relating to the programs which are to be broadcast. A television viewer can thus, from his television, directly access the information of interest to him.
A particularly useful and user-friendly system would offer the viewer the possibility of having information relating to the program currently being broadcast displayed live on his screen. This display (superimposed on the picture or spatially offset) would then be automatic, and would last for example for a few seconds, or would be activated by the user.
However, such a system would require synchronization between the program currently being broadcast and the display of the complementary information. Now, usually, the initially intended schedules included in the program guides are purely indicative: it is common for the programs not to start and finish without delays of a few minutes or more with respect to these schedules. It even happens that some programs are withdrawn at the last moment, for example when a station chooses to broadcast the end of a sports event until well after the envisaged end schedule, to the detriment of the next transmission. It is therefore not possible to rely on the schedule indications provided by the program guides in order to hope to match up the broadcast audiovisual programs and the displaying of corresponding complementary information.
Of course, at the present time some stations send signals making it possible to identify the program currently being broadcast, but most of them do not have recourse to such a technique, and the programs concerned are of very minority appeal.